GE863 datasheet(12/69 Pages) ETC1

12 / 69 page

Telit GE863-QUAD / GE863-PY

Hardware User guide

1vv0300697, Rev. ISSUE#0, - 21/11/05

page 12 of 69

3.2.1.2 + 12V input Source Power Supply Design Guidelines

• The desired output for the power supply is 3.8V, hence due to the big difference between the

input source and the desired output, a linear regulator is not suited and shall not be used. A

switching power supply will be preferable because of its better efficiency especially with the

2A peak current load represented by the GE863-QUAD.

• When using a switching regulator, a 500kHz or more switching frequency regulator is

preferable because of its smaller inductor size and its faster transient response. This allows

the regulator to respond quickly to the current peaks absorption.

• For car PB battery the input voltage can rise up to 15,8V and this should be kept in mind

when choosing components: all components in the power supply must withstand this voltage.

• A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the

current absorption peaks, a 100μF tantalum capacitor is usually suited.

• Make sure the low ESR capacitor on the power supply output (usually a tantalum one) is

rated at least 10V.

• For Car applications a spike protection diode should be inserted close to the power input, in

order to clean the supply from spikes.

• A protection diode should be inserted close to the power input, in order to save the GE863-

QUAD from power polarity inversion. This can be the same diode as for spike protection.

An example of switching regulator with 12V input is:

GE863 Datasheet(PDF) 12 Page - List of Unclassifed Manufacturers